Daniel r



(No Model.)

D. R. HART.

soanw DRIVER. N0. 417,722.

Patented Dec. 24, 1889.

UNITED STATES PATENT}. OFFICE.

DANIEL R. HART, OF NEW YORK, N. Y.

SCREW-DRIVER.

SPECIFICATION forming part of Letters Patent N 0. 417,722, datedDecember 24, 1889.

Application filed December 8, 1888. Serial No. 293,041. (No model.)

To all whom it may concern:

Be it known that I, DANIEL R. HART, of the city, county, and State ofNew York, have invented a new and useful Improvement in Screw-Drivers,of which the following is a specification, reference being had to theaccompanying drawings, forming part thereof. I

The object of my invention is to provide a screw-driver adapted to enterand fit very closely the slotsof screw-heads, and having its point soformed that'its tendency to slip sidewise during the insertion of ascrew is effectually prevented, and having the two side extremities ofits point strengthened in such manner that danger of fracture thereof isavoided.

My invention is more particularly adapted for round-headed screws; butit may be used with other forms of screw-head.

In the drawings, Figure 1 represents a front View of a hand screw-driverconstructed according to my invention. Fig. 2 is a longitudinal sectionof a portion of the same. Fig. 3 is a front View of a'screw-driver bitadapted to be used in a bit-stock. Fig. 4 is aside view of an ordinarywood-screw, a por-,

tion being broken away to show theslot; and

Fig. 5 is a side view of a portion of a screwdriver of modifiedconstruct-ion and showing a wood-screw partially in section in conjLinction therewith.

a designates. an ordinary wood-screw, having a head portion 1), providedwith a slot 0 to receive the screw-driver, the bottom ofwhich slot hasthe ordinary concave form.

d is a screw-driver provided with a handle 6, having its point f made inconvex form, so as to correspond with and fit upon the concave orarc-shaped bottom of the slot 0. The sides of that portion d. of thescrew-driver which engages with the slot are sunk in the sides of theblade and provided with concave shoulders (Z in the rear thereof, andthe portion 01 may be made parallel or to taper slightly in'thicknessfrom the point f, having less thickness at the part g than at the pointf. The concave shoulders d extend rearwardly from the edges of the bladenear its point toward the center of the portion d and correspondapproximately with the form of round-headed screws, and also have arounded or cove-like junction d with the said portion (1. These concaveshoulders may extend entirely to the point at the side extremitiesthereof, if desired; but I preferably terminate them at a suflicientdistance therefrom to allow of the insertion of the point in the slots,

. It will be seen from the foregoing construetion that the fullthickness of the blade extends to within a short distance of its point,and that-the side extremities of the sunk portion, and where the moststrain occurs, tending to fracture the point, are thereby strengthenedwithout interfering with its insertion in the slot. It will also be seenthat by reason of the concave shoulders at the rear of the sunk portionno slipping ot' the screw-driver from the slot sidewise can occur whenit is in use.

Having now describedmy invention, what I claim as new, and desiretosecure by Letters Patent, is

1. A screw-driver having a sunk portion at its point adapted-inthickness to enter and fit the slots of screw-heads, the rear of saidsunk portion having concave shoulders to correspond approximately withthe form of round-headed screws, substantially as described.

2. A screw-driver having a sunk portion at its point adapted inthickness to enter and fit the slots of screw-heads, the rear of saidsunk portion having concave shoulders and a rounded or cove-likejunction with the said sunk portion, substantially as described.

3. A screw-driver having a sunk portion at its point convexin front andadapted in thickness to enter the slots of screw-heads, the rear ofsaidsunk portion having concave shoulders, substantially as described.

4. A screw-driver having a sunk portion at its point, convex at itsfront end, and having concave shoulders at its rear, and the said sunkportion tapering in thickness, substantially as described.

DANIEL R. HART.

Witnesses:

PHILIP J. OREILLY,

JOHN F. HART.

